西天山阿吾拉勒地区A型流纹斑岩的初步研究  

Study on the A-Type Rhyolite Porphyries from the Awulale Area,Western Tianshan

作　　者：李宁波[1,2] 单强[1] 张永平[3] 罗勇[4] 杨武斌[1,2] 姜玉航[1,2] 于学元[1] 

机构地区：[1]中国科学院广州地球化学研究所矿物学与成矿学重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]新疆维吾尔自治区地质矿产勘查开发局第三地质大队,新疆库尔勒841000 [4]南阳师范学院环境科学与旅游学院,河南南阳473061

出　　处：《大地构造与成矿学》2012年第4期624-633,共10页Geotectonica et Metallogenia

基　　金：国家自然科学基金(批准号:41173040)资助

摘　　要：新疆阿吾拉勒山是中亚造山带的重要组成部分。通过对区内火山岩的主量元素和微量元素地球化学研究,在群吉萨伊-塔尔得套一带下二叠统乌朗组中厘定出了一套铝质A型流纹斑岩。群吉萨伊和塔尔得套的流纹斑岩具有富硅(SiO2≥69.9%)和富碱(Na2O+K2O≥7.06%)的特征。其中,塔尔得套流纹斑岩的总碱含量低于群吉萨伊流纹斑岩,但其K2O含量则明显高于后者,属于高钾火山岩。二者均具有明显的Ba、Sr、Eu和Ti亏损,稀土总量在90.7×10-6～264×10-6之间。主量元素和微量元素特征显示,群吉萨伊和塔尔得套的A型流纹斑岩的源区均与硬质砂岩相似,属于A2型花岗岩,同时具有较高的锆饱和温度(TZr约900°C),其成因可能与后俯冲阶段的岩石圈拆沉过程有关。The Awulale Mountains is an important polymetallic metallogenic belt in the Central Asian Orgenic Belt（CAOB）.Based on the major and trace element geochemical features,a suite of A-type aluminous rhyolite porphyries has been recognized in the Lower Permian Wulang Formation in the Qunjisayi and Taerdetao areas.The Qunjisayi and Taerdetao A-type rhyolite porphyries are high-silica（SiO2≥69.9%） and high-alkali（Na2O＋K2O≥ 7.06%）.The A-type rhyolite porphyries from the Taerdetao area are relatively lower in alkali but higher in K2O,which should belong to high-K volcanic rocks.Both A-type rhyolite porphyries from the Qunjisayi and Taerdetao areas are obviously low in Ba,Sr,Eu and Ti with total REE rangeing from 90.7×10-6 to 264×10-6.The Qunjisayi and Taerdetao A-type rhyolite porphyries were probably derived from partial melting of the metagrewacks.The trace element features show that those rhyolite porphyries exhibit A2-subtype geochemical characteristics and were formed under post-collisional setting.The zirconium saturation temperature（T Zr） of the rhyolites is ～900°C.Accordingly,we inferred that the formation of the Qunjisayi and Taerdetao A-type rhyolite porphyries was related to the post-subduction delamination of the thickened lithosphere.

关 键 词：西天山 阿吾拉勒 群吉萨伊 塔尔得套 A型流纹斑岩 后碰撞 

分 类 号：P595[天文地球—地球化学]